A few weekends ago, Dick Arnett, WB4SUV, set a foxhunt at a local hamfest. As a relatively new foxhunter, I'm always envious of the gear the more experienced guys have built and acquired. I'm especially envious of the really small, low power transmitters.  Dick's hunt included 17 transmitters, all on 2m, ranging from microwatt outputs up to one of our regular 2m ARDF transmitters. Photos of the hamfest and the transmitters, including his infamous transmitter in a stick of wood.

The funniest thing to me was that Dick actually stayed up late making more small transmitters (Photos).



He used Joe Leggio's 40mW 2m transmitter design. It looks like the one hard-to-get component is the crystal of approximately 48MHz.  Everything else is readily available, or easy to substitute with something close.

I'm a QRPer.  QRP is the ham radio Q-signal for "Reduce Power".  It's sort of a movement that joins two ideas: (1) Using low power, 5W or less, to make contacts, and (2) making simple, low-power gear. Usually simple.  QRPer's build using the whole range of techniques, from commercial kits with double-sided, through-plated-hole Printed Circuit Boards (PCBs) to building the circuit point-to-point, piece-by-piece above a piece of unetched copper PCB.

Building point-to-point is usually called "ugly construction".  One variant of ugly is "dead bug", where an integrated circuit is mounted with its legs up, like a dead bug on its back.  When ugly construction gets complicated, it's common to hold an electrical node above the copper with a 1 Megaohm or greater resistor as a standoff. People who build radios this way say the radio tends to be more stable than the same circuit with a PCB, due to the copper plate being a ground plane, and the layout tending to be more open, with less opportunity for coupling. QRPer's don't usually build circuits that operate in the 2m band, though.



Joe Leggio's and Dick Arnett's transmitters both use little squares of PCB material that are CA-glued down to the blank copper PCB for the nodes that are above ground. It looks like these were cut with tin snips.  

The first time I'd heard of this method, Jim Kortge, K8IQY, used an Adel Nibbler




to make little rectangles of PCB that are about 6mm long and maybe 2mm wide. Instead of 1 Megaohm resistor standoffs, the standoffs are little copper pads.  When he used these all over the PCB, it reminded him of an aerial view of Manhattan, so it became known as "Manhattan Construction."  And that name has stuck, even though the most common pads now are round, and the preferred tool is a



Roper-Whitney "Number 5 Junior" Punch or a cheap copy of it. The round pads are typically 1/8 to 1/4 inch (3mm to 6mm) diameter. There's even a tool that cuts away the copper to make an island on the board, the New Jersey Islander.

Some really nice articles on Manhattan Construction are available. Paul Harden, NA5N, has one here, and Chuck Adams, K7QO, has two, here and here.

The one problem with this type of construction is the difficulty to make it reliable enough for carrying out into the woods week after week, with occasional drops onto pavement. It's pretty hard to beat a PCB. If you make good solder joints and can get the glue joints to stick, that will go a long way to making these reliable. Most people use medium viscosity CA glue (super glue), which is available at hobby shops.

Another noteworthy detail of Dick's transmitter is the way he packaged it.  It looks like he took a 1x4 board as long as the copper, cut out a hole for the components, and just screwed the copper to the board (See first photo).  Then he added another thin sheet of plywood (1/4 inch or so) as a cover.  He even made a little battery compartment and door.



If I wasn't so far behind on my other kits, I'd build a few of these.

One big difference I see between the QRP and ARDF communities is the number and variety of kits offered by the different people and clubs. Admittedly, QRP is a lot bigger than ARDF, and ARDF does have a few groups and individuals who are kitting up projects to sell, but not nearly enough. There are plenty of designers and published designs, but not enough kits.

I know QRPer's take ridicule because "they're quiet on transmit", but I've heard a lot of people, from ARRL HQ to people without a license, who think the "QRP kit-building and homebrewing ethic" will save ham radio. How many times have you heard someone wax rhapsodic about building a Heathkit? I think ARDF can be part of that same equation. I think ARDF needs more kits, especially for what I call "club gear", gear like a set of five transmitters with built-in controllers that lets a club put on ARDF events.  There are a fair number of receiver kits out there, but not very many transmitter kits.  Our local group here in Cincinnati built 5 TRO-2 transmitters from G3ZOI in England. This is a great design, but it's not really a kit (although I think most amateur clubs would have the expertise and access to test equipment to build them with no difficulty).  What is needed are complete, robust, lightweight transmitter kits, for both 2m and 80m, that can be built in quantities of five by beginning kit builders with only basic test equipment.

If you've never built anything, take the plunge.  It's a lot easier than you might think, especially if you pick the right project. (If anyone knows a good source for crystals, let me know and I'll update this page.)